a1=S1=3*1²+2=5an=Sn-Sn-1(n≥2，n∈N)=3n²＋2-3(n-1)²-2=3(n+n-1)(n-n+1)=3(2n-1)=6n-3当n=1，an=6n-3=6-3=3≠5∴数列{an}的通项公式为a1=5an=6n-3(n≥2，n∈N)请参考
Sn-1＝3（n-1）²+2＝3n²-6n+5an＝Sn-Sn-1＝3n²+2-（3n²-6n+5）＝6n-3
